IPv6

IPv6 is version 6 of the Internet Protocol.

IPv6 is the second version of the Internet Protocol to be widely deployed, and is expected to form the basis for future expansion (as of 2001) of the Internet, replacing the previous standard, IPv4.

The compelling reason behind the formation of IPv6 was lack of address space, especially in the heavily populated countries of Asia such as India and China among others which do not have enough address space for their use.

Table of contents

1 Syntax 2 IPv6 addressing 3 IPv6 deployment 4 Related IETF working groups 5 External links

Syntax

There are eight groups of 4 digits each. The Hexadecimal number system is used for the digits. Thus each group occupies 16 bits of space and the entire address represents (but does not always require) 128 bits.

For example, 3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344. is a valid address

If a 4 digit group is 0000, it may be omitted, thus in the syntax of IPv6

3ffe:6a88:85a3:0000:1319:8a2e:0370:7344  is the same as
3ffe:6a88:85a3::1319:8a2e:0370:7344

Following this rule, if more than two consecutive colons result from this omission, they may be reduced to two colons, as long as there is only one group of more than two consecutive colons. Thus

2001:2353:0000:0000:0000:0000:1428:57ab 
2001:2353:0000:0000:0000::1428:57ab 
2001:2353:0:0:0:0:1428:57ab
2001:2353:0::0:1428:57ab
2001:2353::1428:57ab  
are all valid and mean the same thing,

but  2001::25de::cade is invalid.

Also leading zero's in all groups can be omitted, thus

2001:2353:02de::0e13

is the same thing as

2001:2353:2de::e13

If the address is an IPv4 address in disguise, the last 32 bits may be written in decimal; thus

::ffff:192.168.89.9 is the same as 
::ffff:c0a8:5909, but not the same as
::192.168.89.9 or
::c0a8:5909.

The ::ffff:1.2.3.4 format is called a IPv4-mapped address, and is deprecated. The ::1.2.3.4 format is a IPv4-compatible address.

IPv6 addressing

The most dramatic change from IPv4 to IPv6 is the length of the network addresses used. IPv6 addresses, as defined by RFC 2373 and RFC 2374, are 128 bits long and are written in hexadecimal with colons. The number of available addresses in IPv6 is 2¹²⁸ = 3.4 x 10³⁸ (cf. 2³² = 4 billion addresses in IPv4). Another way to calculate is is 16³² as there are 16 combinations per each digit and 32 digits.

In some situations, IPv6 addresses are composed of two logical parts: a 64-bit network prefix, and a 64-bit host-addressing part, mechanically generated from the interface MAC-address.

IPv6 deployment

To do:

• 6 to 4
• 6bone

Related IETF working groups

• 6bone IPv6 Backbone
• ipng IP Next Generation (concluded)
• ipv6 IP Version 6
• ipv6mib IPv6 MIB (concluded)
• multi6 Site Multihoming in IPv6
• v6ops IPv6 Operations

External links

• http://www.iana.org/assignments/ipv6-address-space